In the Task Board, the "TO DO" of a task cannot be reordered by drag-and-drop, can't change the order when you hover the cursor over a "TO DO" item, there is a holder in front of the circle - this makes the user to expect to be able to drag-and-drop.
Steps to locate the 'To Do' page:-
1. From PPM please click on 'Home' -> click on 'Link to New User experience'
2. Go into a project -> click on 'TASKS' from the menu
3. Click on 'To Do' (the icon is a tick in a box) which is located on the right hand pane
<Please see attached file for image>
We have not implemented drag and drop for To Do's, we are planning this for a future release.